Born George Kellis ca. 1953 in Rhodes, he came to Australia early in life, and was raised in Adelaide. He served as a priest on the Gold Coast, and for the most part of his service in Australia, he was an archimandrite at St Nectarios Monastery, Adelaide.

After a period of time in Adelaide, he felt called to missionary work. He then went to Madagascar and began to evangelise, beginning only with a non-functioning church in the capital. In 1997, Archimandrite Nektarios was elected bishop of the newly created Diocese of Madagascar.

In September 2004 he, along with Pope and Patriarch of Alexandria Petros VII, two other metropolitans, and two priests reposed in a helicopter crash en route to Mount Athos. He was buried in Madagascar.